Enhanced color change interlocking closure strip

ABSTRACT

An interlocking closure device including two closure elements arranged to be interlocked over a predetermined length, each of said closure elements having different colors for establishing visually the completeness of the occlusion of the closure elements by providing color different from the closure elements when said closure elements are occluded, wherein the improvement comprises the introduction of a color change enhancement member in the internal channel of a translucent closure element whereby the closing and opening of the closure device is more easily detected by visual inspection.

FIELD OF THE INVENTION

The instant invention relates to interlocking colored closure stripshaving improved color change characteristics when viewed in theiroccluded form. These interlocking colored closure strips may be employedas fasteners in traditional fastener areas and find particular use asclosures for storage containers, e.g., plastic bags.

BACKGROUND OF THE INVENTION

The use of closure fastening devices for the closure of containers,including plastic bag bodies, is generally known. Furthermore, themanufacture of closure fastening devices made of plastic materials isgenerally known to those skilled in the art relating to closurefastening devices as demonstrated by the numerous patents in this area.

A particularly well-known use for closure fastening devices is inconnection with a flexible container, e.g., bag bodies. The closurefastening device and the associated container may be formed fromthermoplastic materials, and the closure fastening device and sidewallsof the container can be integrally formed by extrusion as a singlepiece, or may be formed as separate pieces and then connected by heatsealing or other suitable fastening means.

The closure fastening devices incorporated as closures on bag bodieshave been particularly useful in improving the retention of contents inthe bag body when the closure is closed. In general, the closurefastening devices on bag bodies have been transparent and the bag bodyhas been made of transparent plastic, thus having the same generalappearance for the closure and the bag body. The use of the sametransparent plastic for the bag body and the male closure and femaleclosure that form the closure fastening device made it difficult toactually determine when the male and female closures were occluded,i.e., when the bag was closed. Since misalignment of the relativelynarrow male and female (typically 90 mils to 120 mils wide) closurescould easily occur, there existed a reasonable likelihood that the bagbody was at least partially open.

The aforementioned occlusion problem arises from the inability of theuser to have a means for identifying when the male and female closureare occluded to form a seal between the contents of the bag and theenvironment external to the inside of the bag. A solution to thisproblem is disclosed in U.S. Pat. No. 4,186,786, U.S. Pat. No. 4,285,105and Japanese Patent Application No. 51-27719. A color change means forverifying the occlusion of the male and female members of the closure isprovided wherein male and female members having different colors areemployed and upon occlusion provide a yet different color. For example,the female member of the closure may be opaque yellow and the malemember of the closure may be translucent blue. Upon occlusion of themale member and female member a composite color with a green hueresults. This use of a color change greatly improves the ability of theuser of the interlocking closure device to determine when the male andfemale members are occluded. Of course, the relative perceivabledifference between the colors of the male member, female member and theoccluded female/male members is the critical variable that impacts onhow well the user of the bag will be able to ascertain when the bag isopen or closed.

The change in color that is viewed when dissimilarly colored male andfemale members are occluded is demonstrated in a commercially availableproduct sold under the trademark GLAD-LOCK (GLAD-LOCK is the registeredTrademark of First Brands Corporation, Danbury, Conn.). The femaleclosure is an opaque yellow and the male closure is a translucent blue.When the male member and female member are occluded, the resulting colorhas a green hue and provides a color change indicating that the bag bodyis closed along the length of the closure fastening device. Asaforementioned, the ability to ascertain whether the closure device isopen or closed is related to the ability of the user to view the changein color of the occluded or unoccluded male and female members of theclosure fastening device. Accordingly, any improvement in the relativecolor change between the male member and female member and the occludedmale and female members will provide for improved ease in using theclosure device and improved closure device's reliability.

FIGS. 1, 2 and 3 show closures devices that have heretofore beenemployed as closures on bag bodies. The closure shown in FIG. 1 has beenemployed as a colored interlocking closure in the manner disclosed inU.S. Pat. Nos. 4,186,786 and 4,285,105. In contrast, the closures shownin FIG. 2 and FIG. 3 have not heretofore been associated with coloredinterlocking closure devices. Instead, the closures of FIG. 2 and FIG. 3have heretofore been employed as transparent closure devices havingsubstantially the same transparent coloration as the bag body. Ashereinbefore discussed, the use of closures having the same color forthe male and female closure elements makes it difficult to visuallyinspect the closure and reliably detect if the closure is open or closed(occluded). This problem may be particularly troublesome for the closuredevices shown in FIGS. 2 and 3 because those closures are relativelysmall, e.g., less than about 250 mils in width, and, therefore, are noteasily grasped for reliable closing. The particular problem associatedwith aligning and closing small closure elements is discussed inEuropean Patent Application No. 83112946.5. As noted in the EuropeanApplication, the use of additional ribs on either side of the closureelements has been suggested in the prior art to give an improved "feel"to the closure to provide a stiffer "feel" to the closure and aid inalignment of the closure elements. While the aforementioned EuropeanPatent Application addresses an improved manufacturing method forforming the disclosed ribs adjacent the closure element, the problem ofvisually being able to determine when the closure device is open orclosed was not addressed.

The objective in closing an interlocking closure device is best met ifthe device is both easy to handle (handleability) and easily capable ofinspection to determine when the closure device is open or closed. Theinstant invention is advantageous in that the color change in the colorchange closure is improved and the instant invention ameliorates theproblem that arises as a result of the presence of additional ribs orguide members on colored interlocking closure devices by including acolor change enhancement member in the internal channel of the maleand/or female closure members. The presence of a color changeenhancement member in the closure channel formed by differently coloredmale and female members has not been disclosed heretofore for providingimproved color change characteristics to color change closure devices.Heretofore, internal elements, e.g., the spring element shown in FIG. 7of U.S. Pat. No. 4,212,337 as being present in the channel of the maleclosure element, have not been disclosed to provide any color changefunction but have been provided solely for sealing. The instantinvention relates in one aspect to improved color changes in colorclosure devices. In another aspect the invention relates to improvedcolor change in wider color closure fastening devices, since it has beenobserved that in such wider closures (e.g., up to about 250 mils, i.e.,wider male and/or female members, closure elements, that there is adecrease in the discernible non-occluded/occluded color change of thetranslucent male and/or female members as the closure is made wider.Therefore, the instant invention relates to improved color changeperception in new closure devices with wider male add/or female closureelements. These wider closures may also have adjacent guide membersintegrally located adjacent to the male and/or female elements of theclosure fastening device. It has been observed that while such "ribs" or"guide members" improve the "feel" of the closure change between thenon-occluded and occluded male and female closure elements.

SUMMARY OF THE INVENTION

The instant invention generally relates to interlocking closure devicesincluding two closure elements arranged to be interlocked over apredetermined length.

Each of these closure elements have different colors and visuallyestablish the completeness of the occlusion of the closure elements byproviding a perceivably different color from that of either closureelement when the closure elements are occluded. The change in colorobserved by occlusion of the closure elements is improved by the instantinvention by introducing a color change enhancement member in theinternal channel of either closure element. Further, it is believed thatuse of a color change enhancement member in a translucent closureelement is particularly beneficial to the perceivable color change whenside guide members are provided adjacent the male and/or female closureelements. This is particularly beneficial when the color changeenhancement member is associated with a translucent female element andguide members are associated with an opaque male element. It has beenobserved that these guide members may interfere with the visualdetermination of the color change of the closure as determined by thecolor of the non-occluded male and female closure elements when comparedto the color of the occluded male and female closure elements.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a prior art closure device.

FIG. 2 is a cross-sectional view of a prior art closure device.

FIG. 3 is a cross-sectional view of a prior art closure device.

FIG. 4 is a cross-sectional view of one embodiment of a female closureelement according to the invention showing the relative dimensions ofthe various elements of the female closure element.

FIG. 5 is a cross-sectional view of one embodiment of the closurefastening device in accordance with the invention in an occludedposition having a generally spike-shaped (isosceles triangle-shaped)color change enhancement member extending from the base portion offemale closure element.

FIG. 6 is a cross-sectional view of another embodiment of the closurefastening device in accordance with the invention in an occludedposition having a generally right triangle-shaped color changeenhancement member extending from the base portion of the female closureelement and having guide members on either side of the male closureelement.

FIG. 7 is a cross-sectional view of the closure fastening device shownin FIG. 6 in a non-occluded position having a generally righttriangle-shaped color change enhancement member extending from the baseportion of the female closure element and having guide members on eitherside of the male closure element.

FIG. 8 is a computer simulated light scattering diagram showing thelight scattering influence of the color change enhancement member shownin FIG. 7 as a generally right triangle-shaped member.

FIG. 9 is a computer simulated light scattering diagram showing thelight scattering influence of a color change enhancement member having agenerally right triangle-shaped and having the generally perpendicularside of the generally right triangle-shaped color change enhancementmember in a configuration that is reversed from that shown in FIG. 8.

FIG. 10 is a computer simulated light scattering diagram showing thelight scattering pattern of the female closure element as shown in FIG.1.

FIG. 11 a computer simulated light scattering diagram showing the lightscattering pattern of the male element shown in FIG. 7 of U.S. Pat. No.4,212,337 having the sealing element shown therein bent away fromincoming light.

FIG. 12 similar to FIG. 11, except the sealing element towards theincoming light.

FIG. 13 is similar to FIG. 11, except the sealing element is not bent inrelation to the incoming light.

FIG. 14 is a simulated computer light scattering diagram showing thelight scattering pattern of the female closure element shown in FIG. 2.

FIG. 15 is a cross-sectional view of another embodiment of the closurefastening device in accordance with the invention in an occludedposition having a generally spike-shaped color change enhancement memberextending from the base of the female closure element and having guidemembers on either side of the male closure element.

FIG. 16 is a cross-sectional view of another embodiment of the closurefastening device in accordance with the invention in an occludedposition having a generally double spike-shaped color change enhancementmember extending from the base portion of the female closure element andhaving guide members on either side of the male closure element.

FIG. 17 is a cross-sectional view of another embodiment of the closurefastening device in accordance with the invention in an occludedposition having two generally stacked and overlapping triangle-shapedmembers as the color change enhancement member extending from the baseportion of the female closure element and having guide members on eitherside of the male closure element.

FIG. 18 is similar to FIG. 17, except that the color change enhancementmember comprises two of the color change enhancements described in FIG.17.

FIG. 19 is a perspective view of a flexible container including aclosure fastening device in accordance with the invention.

FIG. 20 is a diagram that depicts the physical characteristics of thespecial relationships of the color change enhancement member in relationto the closure legs and closure base of the closure element.

FIG. 21 a cross-sectional view of one embodiment of a male closureelement according to the invention suitable for use with the femaleclosure element of FIG. 4 and showing the relative dimensions of thevarious elements of the male closure element.

DETAILED DESCRIPTION OF THE INVENTION

The instant invention provides interlocking closure devices havingimproved color change characteristics when viewed in their non-occludedposition in comparison to their occluded position. The interlockingclosure devices include two closure elements arranged to be interlockedover a predetermined length, each of the closure elements havingdifferent colors for establishing visually the completeness of theocclusion of the closure elements by providing a combined colordifferent from the closure elements that are occluded. It has beendiscovered that the perceivable color change is related to the width ofthe closure elements, the presence of guide members on the closureelement(s) and combinations of these factors. The occluded color changeis enhanced, i.e., is more perceivable to the viewer, by introducing acolor change enhancement member in the internal channel of a translucentclosure element whereby the color change of the closure elements beforeas compared after occlusion is improved when compared with the colorchange of a substantially similar closure device but as determinedwithout the color change enhancement member. The terms "male" and"female" closure element are generally understood in the art as closureelements wherein the element that interlocks into the other closureelement and having outwardly projecting hooks is referred to as the"male closure element" and the outer element is referred to as the"female closure element" and has inwardly projecting hooks. These termshave been employed to define closure elements without any guide members.The characteristics of this color change enhancement member and itsrelationship to the male and female closure elements is discussedhereinafter.

The color change enhancement member may be provided to enhance the colorchange in a wide variety of interlocking closure fastening devices whensuch are used as color change closures. A "color change closure"comprises a combination of a male closure element of one color, a femaleclosure element of a different color which upon occlusion provide athird and perceivably different color. The interlocking closurefastening device may be as shown in U.S. Pat. No. Re. 28,969, 4,212,337or as shown in FIG. 5 of U.S. Pat. No. 3,054,434, copending U.S. Ser.No. 774,400, filed Sept. 11, 1985 and U.S. Ser. No. 774,997, filed Sept.11, 1985 each of the aforementioned items incorporated herein byreference. The interlocking closure fastening devices disclosed incopending U.S. Ser. Nos. 509,388, filed June 30, 1983 and 690,207, filedJan. 10, 1985, incorporated herein by reference may also be employed inthe instant invention as the closure to which the color changeenhancement member is introduced when such closure devices are employedas a color change closure device. In addition, guide members may beprovided adjacent each of the aforementioned closures of said patents.

The nature of the relationship of the color change enhancement member tothe interlocking closure fastening device of which it is an integralpart is subject to several variables. These variables include theparticular optical properties of the closure elements without a colorchange enhancement member, the geometry of the color change enhancementmember and its light directing properties, the individual and combinedoptical properties of the aforementioned closure elements and thephysical characteristics of the material of construction, e.g., selectedplastic, coloration pigments, etc., of the male and female elements ofthe interlocking closure fastening device. The particular relationshipbetween the color change characteristics of a color change closure isrelated to the geometry of the color change enhancement member. Suchgeometrical considerations include the height, width, shape (faceangles) and the relative position of the color change enhancement memberwithin the closure element. In addition, the selected geometry of thecolor change enhancement member is related to the light scatteringcharacteristics of the closure element independent of the color changeenhancement member and also when considered in combination with thecolor change enhancement member. The light scattering characteristics ofthe closure element are influenced by the depth of the channel of theclosure element, the presence of guide members, the width of the closureelement and the like. In addition, characteristics of the plasticmaterial of construction, including pigments, TiO₂ concentration, andthe like may affect the color change characteristics of a color changeclosure.

The nature of the color selection for a male closure element and/orfemale closure element has been described in U.S. Pat. No. 4,186,786 atcolumn 3, beginning at line 42 to column 4, line 2, incorporated hereinby reference. The selection of the colors of the closure elements aswell as the use of translucent or opaque closure elements has heretoforebeen a matter of selection. In all instances at least one of the closureelements will be translucent and act as the closure element throughwhich the color change is viewed. In one embodiment closure element isopaque as compared to the other closure element with which it interlockswhich is translucent. When one of the closure elements is opaque thecolor change enhancement member will be associated with the translucentclosure element.

It has been discovered that while it is beneficial to have a colorcombination of closure elements wherein one closure element is atranslucent blue and the other closure element is opaque yellow it maybe preferable to have just the opposite combination, i.e., have atranslucent yellow closure element for occlusion with an opaque blueclosure element. It is believed that such may be preferred because ofthe ability of the human eye to preferentially perceive distinctions invarious wavelengths of light.

As aforementioned, the actual shape of the color change enhancementmember is related to the geometry of the selected interlocking closuredevice and may be selected to provide for improved perceived colorchange for a given color change closure. The importance of thecorrelation of the color change enhancement member to the othercharacteristics of the closure fastening device is readily apparent whenthe width of the closure is greater than about 120 mils. These widercolor change closure fastening devices may result when guide members areprovided on either side (adjacent outside faces of closure legs) of themale element and/or female element or when the closure fastening deviceis simply made wider. In both the wider closures and when guide membersare provided adjacent to the male and/or female closure elements, theoptical properties of the closure fastening device adversely affectedthe light transmitting properties of the closure elements which affectthe perceivable color change that is determined between the initiallyunoccluded closure elements and the occluded male and female closureelements.

Surprisingly, it has been discovered that by providing a color changeenhancement member in the channel of either a male or female translucentclosure element of a color change closure that the color changecharacteristics of the closure color change are improved. Theimprovement in color is particularly beneficial when the width of theclosure fastening device is greater than about 120 mils and/or whenguide members are provided adjacent the male and/or female closureelement. Two different effects are observed as a result of each of thesechanges in the closure fastening device. As the width of the closureelements increase the larger flat bases of the closure elements act aswindows that permit the passage of light into the closure element. Thisincrease in light has a negative effect on the ability to perceive acolor distinction between closely placed but non-occluded male andfemale closure elements and the occluded male and female closureelement. The increase in light that enters the wider base of thetranslucent closure element decreases the perceivable color differenceon closely placed yet non-occluded closure elements by permittingviewing of the combined color of the opaque closure element and thetranslucent closure element prior to occlusion. This gives a viewer afalse indication of occlusion, since a color change may be observed whenthe closure elements are aligned and occlusion has not yet occurred. Incontrast, the presence of guide members on a closure element arebelieved to interfere with light that would enter the closure elementand, in fact, therefore do not improve the color change characteristicsof a color change closure.

The improvement in color definition of the closure device is two-fold.The color change between the male and female closure elements is judgedby viewing the male and female closure elements in close proximity butnon-occluded and then comparing this color with the color viewed uponocclusion of the closure elements. The introduction of a color changeenhancement member provides an improvement in the aforementionedperceivable color change. Although not wishing to be limited to anyparticular theory, it is believed that the color change enhancementmember provides several functions. The color change enhancement memberimproves the individual color characteristics of the translucent closureelement of which it is an integral part, which in turn improves thecolor change distinction of the non-occluded male and female closureelements and the occluded male and female closure elements. The colorchange enhancement member acts as a light directing member thatredirects light entering the sides of the closure element (see: FIG. 8)and directs it to the area viewed by the user of the color changeclosure in evaluating the change in color of the occluded closureelements as compared to the non-occluded male and female closureelements. This aspect is particularly beneficial when the male andfemale closure elements are placed in close proximity, since light thatcould have entered the translucent closure element having the colorchange enhancement member is now at least partially blocked by the otherclosure element.

The shape of the color change enhancement member and its position inrelation to the closure element of which it is an integral part isselected to act as a means for improving the observed color differenceof the non-occluded male and female closure elements and the occludedmale and female closure elements which are a different color than thatobserved upon occlusion of male and female closure elements. Therelationship of the physical characteristics of the closure element withassociated color change enhancement member is shown in FIG. 20. Incidentlight 420 enters closure element 422 through outside leg 424 via outsideleg face 426. This incident light is shown in FIG. 20 as perpendicularto the outside leg face. It will be appreciated that without a colorchange enhancement member that such perpendicular light rays are likelyto pass through the legs of the closure element instead of the closurebase and that without re-direction to the closure base this light willnot be used for illuminating the closure base. The light passes incidentto the color change enhancement member where it is directed downward andpreferably is directed through closure base 430 at a point within thechannel of the closure element. The light is preferably directed withinthe channel of the closure element before the point where inside legface 434 of the inside closure leg 436 meets closure base 430 atinterface 432. The terms "inside" and "outside" are employed herein torefer to the legs of the closure element where light enters the closureelement (outside) for direction by the color change enhancement memberand the closure leg towards which this light is directed by the colorchange enhancement member (inside). It is understood that thedesignation of either leg of the closure element as "inside" or"outside" is made herein for ease of explanation of the light directingproperties of the color change enhancement member. In fact, each leg ofthe closure element acts as an outside leg since incident light passesthrough both translucent closure legs.

The correlation of the geometric shape of the color change enhancementmember to the desired optical properties of the closure element ischaracterized in FIG. 20 wherein the direction of a perpendicular lightray through a non-occluded female or male closure is shown to depend onseveral factors which are correlated by the following relationship:

    H/Tan (Asin [Nsinφ]-φ)+(H.sub.t -H)Tan(φ)≦D

wherein N is the index of refraction of the material that is used tomake the closure element; H is the height of the incident light rayabove the base of the closure element; H_(t) is the total height of thecolor enhancement member as measured from the base of the closureelement; φ (phi) is the angle at the top of the color change enhancementmember; and D is the horizontal distance between the light incidentfirst face of the color change enhancement member and the intersectionof the inner face of the inner leg and the base portion of the closureelement. Referring to FIG. 20, the color change enhancement member isgenerally shown as having the face upon which light enters the member asgenerally parallel to the first leg of the closure element. It will beappreciated that in embodiments according to this invention that theincident light surface of the color change enhancement member may beother than generally parallel to the first leg of the closure elementand this will result in a reduced light-directing function for the sameangle φ (phi). The correlated relationship of the above factors is suchthat improvement in the lighting of the closure element results fromside light entering through a translucent leg of the closure element.Redirection of this light is achieved when the left hand side of theaforementioned relationship is less than or equal to D and preferablywhen it is less than D. The actual dimensions of a representative femaleclosure element having a right triangle-shaped color enhancement memberis shown in FIG. 4 where the values for the dimensional parameters onFIG. 4 are (given in mils):

    ______________________________________                                        Parameter    Range (mils)                                                                             Preferred (mils)                                      ______________________________________                                        Z            50-70      55-65                                                 Y            01-55      23-33                                                 X            06-16       9-13                                                 W            120-140    125-135                                               V            01-41      16-26                                                 U            62-82      67-77                                                 T             05-105    50-60                                                 S            48-68      53-63                                                 ______________________________________                                    

A male closure element for use in conjunction with the female closureelement of FIG. 4 is shown in FIG. 21 wherein the dimensional parametersare (given in mils):

    ______________________________________                                        Parameter    Range (mils)                                                                             Preferred (mils)                                      ______________________________________                                        A            30-50      35-45                                                 B            10-16      11-15                                                 C            28-48      33-43                                                 D            170-190    175-185                                               E            73-93      78-88                                                 F            10-50      25-35                                                 G            13-23      16-20                                                 H            31-51      36-46                                                 ______________________________________                                    

In a closure fastening device having a color change enhancement memberwhere the quantity H/Tan (Asin [N(sinφ]-φ)+(H_(t) -H)Tan(φ) is less thanor equal to D (see FIG. 20) the incident light entering the closure isdirected toward the base of the closure element and serves to illuminatethe base of the closure element.

Generally, the closure elements of this invention that form the closurefastening devices may be formed from thermoplastic materials such aspolyethylene, polypropylene, nylon, or the like, or from a combinationthereof. Thus, resins or mixtures of resins such as high densitypolyethylene, medium density polyethylene and low density polyethylenemay be employed to prepare the novel closure device of this invention.The particular coloration of the thermoplastic material may have anadvantageous affect on the color change characteristics of the closure,since the light dispersing properties of the colored thermoplasticmaterial are important.

In one embodiment the female and male closure elements are as shown inFIG. 6 and FIG. 7. The closure fastening device shown comprises male andfemale closure elements wherein the female closure element has anintegrally formed color change enhancement member and the male closureelement has integrally formed guide members spaced apart from the pairof spaced-apart, parallelly disposed webs that extend generally normalfrom the base of the closure element. In this embodiment one of theclosure elements is an opaque primary color and the other closureelement is a sufficiently translucent primary color which upon occlusionprovides a third color when viewed through the translucent closureelement.

The closure fastening device of the invention may be manufactured byextrusion, or other known methods of producing such devices. The closurefastening device can be manufactured as individual closure elements forlater attachment to a film, or the closure element portions can bemanufactured integral with a film. In addition, the closure fasteningdevice can be manufactured with or without flange portions on one orboth of the closure elements depending upon intended use or expectedadditional manufacturing operations.

In the practice of the instant invention, the closure fastening devicemay be integrally formed with the sidewalls of a container, or connectedto a container, by the use of any of many known methods. Athermoelectric device can be applied to a film in contact with a flangeportion of a closure element or the thermoelectric device can be appliedto a film in contact with the base portion of a closure element havingno flange portion, to cause a transfer of heat through the film toproduce melting at the interface of the film and the flange portion orbase portion of the closure element. The bonding of closure element(s)to the film stock may be carried out either before or after the film isU-folded but in any event is done prior to side sealing the bags at theedges by conventional thermal cutting. The thermoelectric device can beheated rotary discs, or resistance heated slide wires, or travelingheater bands, or the like. The connection between the film and theclosure element can also be established by the use of hot meltadhesives, or hot jets of air to the interface, or ultrasonic heating,or other known methods. Generally, the closure fastening device and thefilms that form the body of the bag can be made from a heat sealablematerial so that a container can be formed economically by heat sealingthe aforementioned components to form the container using thermoplasticsof the type aforementioned for formation of the closure elements.

In addition, the closure fastening device with the color changeenhancement member is more difficult to deocclude from the inside of thecontainers than from the outside of the containers thereby providingmore secure containment of goods such as food products. The elementportions of the closure device have approximately uniformcross-sections. This not only simplifies the manufacturing of the devicebut it also contributes to the physical flexibility of the device, whichis a desirable property.

Generally, the closure fastening device of this invention can bemanufactured in a variety of forms to suit the intended use. Inaddition, the male and female closure elements can be positioned onopposite side of a film. Such an embodiment would be suited forenwrapping an object or a collection or objects such as wires.Generally, the male and female closure elements on a film should beparallel to each other, but this would depend on the intended use.

FIGS. 1, 2 and 3 are prior art closures. The closure of FIG. 1 has beenemployed as a closure in accordance with the disclosure of the U.S. Pat.No. 4,186,786 as a colored interlocking closure strip having a width atits base less than 120 mils. The closures shown in FIG. 2 and FIG. 3 areprior art closures which have not heretofore been associated with colorchange closure strips.

FIG. 4 is a female closure element according to the instant inventionhaving a base portion 30, a pair of spaced-apart parallelly disposedwebs 32 and 34 extending in a generally normal direction from baseportion 30 and having female hook portions 36 and 3 extending from webs32 and 34, respectively, and facing towards each other with color changeenhancement member 40 having a generally right triangle-shaped form withlight generally perpendicular to face 42 and with hypotenuse face 44.The dimensional parameters Z, Y, W, X, W, V, U, T and S have beenheretofore defined.

FIG. 5 shows an embodiment wherein a male element portion 50 isconnected to a flange portion 50 and includes a base portion 54, a pairof spaced-apart, parallelly disposed first webs 56 and 58 extending in agenerally normal direction from the base portion 54, and male hookportions 60 and 62 extending from webs 56 and 58, respectively andfacing away from each other. One of the male hook portions has aninwardly projecting guide surface 64, which generally serves to guidethe hook portions for occlusion with the female hook portions of amating closure element. A female element portion 70 is connected toflange portion 72 and includes a base portion 74, a pair ofspaced-apart, parallelly disposed webs 76 and 78 extending in agenerally normal direction from base portion 74 and female hook portions80 and 82 extending from webs 76 and 78, respectively, and facingtowards each other and color change enhancement member 84 as a generallyspiked-shaped member having opposing faces 86 and 88 characterized ashaving substantially the same length, as measured from midpoint 87 ofmember 84 to the base portion where member 84 abuts base portion 74. Oneof the female hook portions has a rounded crown surface 90, the otherhas an inwardly projecting guide surface 92 which serves to guide thehook portions for occlusion with the male hook portions of a matingclosure element. Closure elements 50 and 70, shown in FIG. 5, may beseparately formed and therefore connected to a firm which formssidewalls of a bag body, or they may be integrally formed with suchsidewalls (as shown in FIG. 19). The color change enhancement member 84shown in FIG. 5 is an isosceles triangle-shaped member having first sideportion 86, second side portion 88, where first and second base sideportions contact closure base 74 at 92 and 94.

Guide members may be added to provide improved "feel" to the closuredevice and may be provided in the shape of triangles, rectangles orother suitable shapes and are generally provided by extrusion as anintegral part of the male and/or female closure elements. Further, theguide members may be provided as outer aligning members that guide themale and female closure elements towards each other. In one embodimentthe guide members extend from the flange portion on each side of themale closure element in a generally perpendicular direction at the basewith an outwardly bending top member such that a funneling-typedirection orientation is provided as the female closure element isbrought into contact with the male closure element. FIG. 6 shows such anembodiment.

As shown in FIG. 6, a male portion 100 is connected to a flange portion102 and includes a base portion 104, a pair of spaced-apart, parallellydisposed first webs 106 and 108 extending in a generally normaldirection from the base portion 104, and male hook portions 110 and 112extending from webs 106 and 108 and facing away from each other. One ofthe male hook portions has an inwardly projecting guide surface 114which generally serves to guide the hook portions for occlusion with thefemale hook portions of a mating closure element. A second pair ofspaced-apart, parallelly displaced second webs 116 and 118 are spacedapart on either outward side of the first spaced apart webs and extendin a generally normal direction at portions 124 and 126 from the baseportion 104 with generally outwardly projecting guide surfaces 120 and122, respectively, to provide guide surfaces for the female closureelement. A female element portion 130 is connected to flange portion 132and includes a base portion 134, a pair of spaced-apart, parallellydisposed webs 136 and 138 extending in a generally normal direction fromthe base portion 134 and female hook portions 140 and 142 extending fromwebs 136 and 138, respectively, and facing towards each other and colorchange enhancement member 144 as a generally right triangle-shapedmember having a generally parallelly disposed first face 146 extendingin a normal direction from the base portion 134, an angularly disposedsecond face 148 and top 150. One of the female hook portions has arounded crown surface 152 and the other has an inwardly projecting guidesurface 154 which serve to guide the hook portions for occlusion withthe male hook portions of a mating closure element. Closure elements 100and 130 shown in FIG. 6 may be separately formed and thereafterconnected to a film which forms sidewalls (not shown) by the flanges 102and 132 or they may be integrally formed with such sidewalls (notshown). The color change enhancement member 148 shown in FIG. 6 is agenerally right triangle-shaped member having substantially firstperpendicular side portion 146, non-perpendicular second side portion144, first and second base contact points 145 and 147 and top 150.

FIG. 7 is similar to FIG. 6 and shows the male and female closureelements of FIG. 6 in a non-occluded position. The relative spatialrelationship of the male and female closure elements prior to occlusionshows the funneling or guide function that the guide members provide asthe male and female closure elements are occluded.

In FIG. 6 and FIG. 7 the guide members have been introduced adjacent andspaced apart from either side of the legs of the male closure element toprovide a wider closure characterized by improved handleability, i.e.,the wider closure has improved "feel" and also such guide membersprovide improved guidance during occlusion. The color change enhancementmember is advantageously employed with an opaque translucent femaleclosure element when the guide members are employed with the maleclosure element, since it is believed that the guide members obstructlight entering the near occluded closure elements, as hereinbeforediscussed. The functional and critical nature of the color changeenhancement member as part of the translucent closure element is moreclearly understood by reference to FIGS. 8 to 14.

FIG. 8 is a computer simulated light diagram showing the effect of thecolor change enhancement member on incident light 160 that enters theside of a translucent female closure element having first leg 162 withouter face 164, second leg 166 with inner face 168, color changeenhancement member 170 with light incident face 172, light directingface 174 and base portion 176. Light passing through leg 164 passesincident to the color change enhancement member 170 incident to face172. The light incident to the color change enhancement member is bentto pass through closure base portion 176 and is preferably bent suchthat the light passes through the base portion of the closure elementbefore it is incident on the inside surface 168 of leg 166. Thedirection of incident light 160 in FIG. 8 is based on the assumptionthat leg 164 will be positioned as the top of the closure device whenplaced on a bag body. For example, in FIG. 19 leg 164 would be adjacentthe top or opening of the bag and would be the portion of the closureelement that has incident overhead light. During normal use of suchcontainers the lighting will be supplied by overhead lighting and,accordingly, the incident light will be primarily in a directiongenerally downward and incident on face 164 of leg 162. It will beunderstood that incident light may also pass through inside leg 166 andbe bent by the color change enhancement member. The reverse orientationof the color change enhancement member of FIG. 8 is shown in FIG. 9where incident light 180 passes through leg 182 having outer face 184and is incident on the non-perpendicular face 188 of color changeenhancement member 186 and is bent so as to pass through base portion192 of the female closure element. As discussed above in relation toFIG. 8 the redirection of the incident light through the base portion ofthe closure element serves to illuminate the color of the translucentclosure element and minimizes the reliance on light from the open faceof the closure element for illumination. This feature is beneficial whenthe male and female closure elements are in close proximity and lightpassing from the open face of the female closure element is obstructedby the male closure element. The illumination benefit provided by thecolor change enhancement member can be appreciated by reference to FIG.10 wherein the female closure element is substantially the same as theno color change enhancement member is present. Incident light 200 isperpendicular to translucent leg 202 then passes through leg 202 andthen passes uninhibited through leg 204. The light is not directedthrough base portion 206 of the closure and provides no benefit inillumination of the closure, since light is not directed through baseportion 206 of the closure.

Comparison between FIG. 8 and FIGS. 11, 12 and 13 show the importance ofhaving a color change enhancement member that functions as a lightdirecting member, i.e., directs light to illuminate the base portion ofa translucent closure element of which it is an integral part. FIG. 11shows the effect of a non-light directing element in a male closureelement as disclosed in FIG. 7 of U.S. Pat. No. 4,212,337. The centerelement shown in FIG. 7 of U.S. Pat. No. 4,212,337 is a spring elementthat is longer than the depth of the channel of the element and ischaracterized by faces that are generally parallel to the faces of thelegs of the closure element. Since the length of the center element 46in FIG. 7 of the patent is longer than the depth of the channel of theclosure element the center element 46 may be either straight, deflectedupward or downward as the male and female closure elements are contactedjust prior to occlusion. FIGS. 11, 12 and 13 show a downward deflection,upward deflection and no deflection of the center member, respectively.

In each of FIGS. 11, 12 and 13 incident light 210 perpendicular to leg212 passes through first leg 212, center member 216 and passes from theclosure element through leg 214. The center element 216 does not act todirect light through closure base 218.

FIG. 14 is a computer simulation of the path that incident light 220follows as it impinges on leg 222 and leg 224 of the prior art femaleclosure element shown in FIG. 2. As shown in FIG. 14 the legs of theclosure element do not direct light to pass through and illuminate baseportion 226 of the closure element.

FIG. 15 is similar to FIG. 6, except the color change enhancement membercomprises a generally isosceles triangle-shaped member wherein the sidesof the isosceles triangle-shaped color change enhancement member havesubstantially the same length. As shown in FIG. 15, a male portion 230is connected to a flange portion 232, and includes a base portion 234, apair of spaced-apart, parallelly disposed first webs 236 and 238extending in a generally normal direction from the base portion 232, andmale hook portions 240 and 242 extending from webs 236 and 238 andfacing away from each other. One of the male hook portions has aninwardly projecting guide surface 244 which generally serves to guidethe hook portions for occlusion with the female hook portions of amating closure element. A second pair of spaced-apart, parallellydisplaced second webs 246 and 248 are spaced apart on either outwardside of the first spaced apart webs and extend in a generally normaldirection at portions 250 and 252 from the base portion 232 withgenerally outwardly projecting guide surfaces 254 and 256, respectively,to provide guide surfaces for the female closure element. A femaleelement portion 260 is connected to flange portion 262 and includes abase portion 264, a pair of spaced-apart, parallelly disposed webs 266and 268 extending in a generally normal direction from the base portion264 and female hook portions 270 and 272 extending from webs 266 and268, respectively, and facing towards each other and color changeenhancement member 274 as a substantially isosceles triangle-shapedmember having a first and second faces 276 and 278 extending in adirection from the base portion 264 wherein the length of the first andsecond faces are substantially of equal length. Closure elements 230 and260 shown in FIG. 15 may be separately formed and thereafter connectedto a film which forms sidewalls (not shown) by the flanges 232 and 262or they may be integrally formed with such sidewalls (not shown).

FIG. 16 is similar to FIG. 15, except the color change enhancementmember comprises two substantially isosceles triangle-shaped memberswherein the sides of the color change enhancement member are ofsubstantially the same lengths, as measured with respect to where facessaid contact the base portion of the closure element. As shown in FIG.16, a male portion 290 is connected to a flange portion 292 and includesa base portion 294, a pair of spaced-apart, parallelly disposed firstwebs 296 and 298 extending in a generally normal direction form the baseportion 294, and male hook portions 300 and 302 extending from webs 296and 298 and facing away from each other. One of the male hook portionshas an inwardly projecting guide surface 304 which generally serves toguide the hook portions for occlusion with the female hook portions of amating closure element. A second pair of spaced-apart, parallellydisplaced second webs 306 and 307 are spaced apart on either outwardside of the first spaced apart webs and extend in a generally normaldirection at portions 308 and 310 from the base portion 294 withgenerally outwardly projecting guide surfaces 312 and 314, respectively,to provide guide surfaces for the female closure element. A femaleelement portion 320 is connected to flange portion 322 and includes abase portion 324, a pair of spaced-apart, parallelly disposed webs 326and 328 extending in a generally normal direction from the base portion324 and female hook portions 330 and 332 extending from webs 326 and328, respectively, and facing towards each other and color changeenhancement members 334 and 336 each comprising a substantiallytriangle-shaped color change enhancement member as described above forFIG. 15.

FIG. 17 is similar to FIG. 6, except the color change enhancement memberis formed from two triangle-shaped members having an uppertriangularshaped member atop a lower triangle-shaped base member. Asshown in FIG. 17, a male portion 350 is connected to a flange portion352 and includes a base portion 354, a pair of spaced-apart, parallellydisposed first webs 356 and 358 extending in a generally normaldirection from the base portion 354, and male hook portions 360 and 362extending from webs 356 and 358 facing away from each other. One of themale hook portions has an inwardly projecting guide surface 364 whichgenerally serves to guide the hook portions for occlusion with thefemale hook portions of a mating closure element. A second pair ofspaced-apart, parallelly displaced second webs 366 and 368 are spacedapart on either outward side of the first spaced apart webs and extendin a generally normal direction at portions 370 and 372 from the baseportion 354 with generally outwardly projecting guide surfaces 374 and376, respectively, to provide guide surfaces for the female closureelement. A female element portion 380 is connected to flange portion 382and includes a base portion 384, a pair of spaced-apart, parallellydisposed webs 386 and 388 extending in a generally normal direction fromthe base portion 384 and female hook portions 390 and 392 extending fromwebs 386 and 388, respectively, and facing toward each other and colorchange enhancement member 394 formed from two right triangle-shapedmember having a upper triangle-shaped member 396 atop a lowertriangle-shaped base member 398. This form of the color changeenhancement member is advantageous in that the light directing effectprovided by the color change enhancement member is obtained by us of asmaller mass of thermoplastic material than would be employed if themember was formed by a single triangular mass, e.g., isosceles or righttriangle shaped color change enhancement member. This smaller mass isbeneficial in the manufacturing closure elements containing the colorchange enhancement member in that there is a reduction in the mass ofthermoplastic material that needs to be cooled after extrusion of theclosure element.

FIG. 18 is similar to FIG. 17, except the change enhancement member isformed by two of the color change enhancement members shown anddescribed in FIG. 17. The two color change enhancement members 400 and402 are shown in FIG. 18 as an integral part of the female closureelement disclosed in FIG. 17. The male closure element of FIG. 18 is thesame as disclosed and described in FIG. 17.

FIG. 19 show a typical flexible container 410 formed from a thin,plastic film which is folded at bottom portion 412 and heat sealed alongthe vertical side edges 413 to from a pouch. The sidewalls 414 extendbeyond the closure fastening device 415 to provide mouth portions 416and 418 to simplify the opening of closure fastening device 414.

FIG. 20 is a schematic diagram showing a perpendicular light ray 420entering face 426 of closure element 422, passing through leg 424 andshown perpendicular to color change enhancement member 428. The colorchange enhancement member 428 is shown as a generally righttriangle-shaped member and has top angle φ (phi). The light directingproperties of color change enhancement member 428 in FIG. 20 show theperpendicular light ray directed to the base of inside closure leg 436to the point of intersection 432 of the inner face 434 of leg 436 andclosure base 430.

FIG. 21 shows the physical dimensions of a male closure element suitablefor use with the female closure element shown in FIG. 4. FIG. 6 shows aclosure fastening device formed by the female closure element of FIG. 4and the male closure element of FIG. 21.

I claim:
 1. An interlocking closure device including male and femaleclosure elements arranged to be interlocked over a predetermined length,each of said closure elements having different colors for establishingvisually the completeness of the occlusion of the closure elements byproviding a color different from the closure elements when said closureelements are occluded wherein at least one of the closure elements istranslucent, wherein the improvement comprises the introduction of atranslucent color change enhancement member, having an index ofrefraction, in the internal channel of a translucent closure elementwherein said color change enhancement member is effective in improvingthe perceivable color change between said male and female closureelements having different colors and the different color formed byocclusion of the differently colored male and female enclosure elements.2. The interlocking closure device of claim 1 wherein said color changeenhancement member is integrally associated with said male closureelement.
 3. The interlocking closure device of claim 1 wherein saidcolor change enhancement member is integrally associated with saidfemale closure element.
 4. The interlocking closure device of claim 1wherein the male closure element comprising a U-shaped channel elementincluding a element portion comprising a base portion having a pair ofspaced-apart, parallelly disposed webs integrally attached to said baseportion and extending therefrom, said webs terminating in hooks, saidhooks comprising hook portions facing away from each other an hookprojections facing toward each other.
 5. The interlocking closure deviceof claim 1 wherein the female closure element comprises an elementportion having a base portion with a pair of spaced-apart, parallellydisposed webs attached to said base portion and spaced-apart to passover said webs on said male closure element, wherein said webs on saidfemale closure element terminate in hooks extending toward each other toengage on said male closure element.
 6. The interlocking closure deviceof claim 5 wherein said color change enhancement member is integrallyassociated with said female closure.
 7. The interlocking closure deviceof claim 4 wherein said color change enhancement member is integrallyassociated with said male closure element.
 8. The interlocking closuredevice of claim 1 wherein the male closure element comprises a U-shapedchannel element including a element portion comprising a base portionhaving a pair of spaced-apart, parallelly disposed webs integrallyattached to said base portion and extending therefrom, said websterminating the hooks, said hooks comprising hook portions facing awayfrom each other and wherein the female closure element comprises aelement portion having a base portion with a pair of spaced-apart,parallelly disposed webs attached to said base portion and spaced topass over said webs on said male closure element, wherein said webs onsaid female closure element terminate in hooks extending toward eachother to engage on said male enclosure element.
 9. An interlockingclosure device according to claim 8 including male and female closureelements arranged to be interlocking over a predetermined length, eachof said closure elements having different colors for establishingvisually the completeness of the closure elements by providing a colordifferent from the male and female closure elements when said closureelements are occluded and wherein at least one of said closure elementshas guide members integrally formed therewith and spaced adjacent to andapart from said closure element.
 10. The interlocking closure device ofclaim 9 wherein said guide members are integrally formed with said maleclosure element.
 11. The interlocking closure device of claim 10 orclaim 13 wherein said guide members are triangularly-shaped.
 12. Theinterlocking closure device of claim 10 or claim 13 wherein said guidemembers are rectangularly-shaped.
 13. The interlocking closure device ofclaim 9 wherein said guide members are integrally formed with saidfemale closure element.
 14. The interlocking closure device of claim 1or claim 8 or claim 9 wherein the male closure element comprises aU-shaped channel element including a element portion comprising a baseportion having a pair of spaced-apart, parallelly disposed websintegrally attached to said base portion and extending therefrom, saidwebs terminating in hooks, said hooks comprising hook portions facingaway from each other said guide members are integrally associated withthe male closure element which is opaque and said color changeenhancement member is integrally associated with the female closureelement which is translucent.
 15. The interlocking closure device ofclaim 14 wherein the female closure element comprises a element portionhaving a base portion with a pair of spaced-apart, parallelly disposedwebs attached to said base portion and spaced to pass over said webs onsaid male closure element, wherein said webs on said female closureelement terminate in hooks extending toward each other to engage on saidmale closure element.
 16. The interlocking closure device of claim 1wherein said color change enhancement member is characterized as havingone face substantially parallel to said pair of spaced-apart, parallellydisposed webs.
 17. The interlocking closure device of claim 1 whereinsaid color change enhancement member has a height less than the heightof said spaced-apart, parallelly disposed webs.
 18. The interlockingclosure device of claim 1 or claim 8 or claim 9 wherein the relationshipbetween the spatial relationship of the translucent closure element andthe geometry of the integrally formed color change enhancement member isdefined by the relationship:

    H/Tan (Asin [N sin pφ]-φ)+(H.sub.t -H) Tan φ≦D

where N is the index of refraction of the material used to make theclosure element; H is the height of The incident light ray above thebase of the closure element; H_(t) is the height of the color changeenhancement member as measured from the base of the closure element; φ(phi) is the angle at the top of the color change enhancement member; Dis the horizontal distance between the light incident first face of thecolor change enhancement member and the intersection of the inner faceof the inner web of the closure element and the closure base of theclosure element.
 19. The interlocking closure device of claim 18 whereinthe quantity

    H/Tan (A sin [N sin φ]-φ)+(H.sub.t -H) Tan φ

is less than D.
 20. An interlocking closure device according to claim 1including male and female closure elements having U-shaped channelsarranged to be interlocked over a predetermined length, each of saidclosure elements having different colors for establishing visually thecompleteness of the occlusion of the closure elements by providing acolor different from the closure elements when said closure elements areoccluded, one closure element being opaque and having guide membersintegrally formed therewith and spaced adjacent to and apart from saidwebs and the other closure element being translucent.
 21. Aninterlocking closure device according to claim 20 including male andfemale closure elements arranged to be interlocked over a predeterminedlength, each of said closure elements having different colors forestablishing visually the completeness of the occlusion of the closureelements by providing a color different from the closure elements whensaid closure elements are occluded; wherein one of the closure elementsis translucent and the other closure element is opaque; wherein the maleclosure element comprises a U-shaped channel element including anelement portion comprising a base portion having a pair of spaced-apart,parallelly disposed webs integrally attached to said base portion andextending therefrom, said webs terminating in hooks, said hookscomprising hook portions facing away from each other; wherein the femaleclosure element comprises a U-shaped channel element including anelement portion having a base portion with a pair of spaced-apart,parallelly disposed webs attached to said base portion and spaced topass over said webs on said male closure element, wherein said webs onsaid female closure element terminate in hooks extending toward eachother to engage on said male closure element.
 22. The interlockingclosure device of claim 1 wherein the width of the closure is greaterthan about 120 mils.
 23. The interlocking closure device of claim 20 orclaim 21 wherein the width of the closure is greater than about 120mils.
 24. An interlocking closure device according to claim 1 includingmale and female closure elements arranged to be interlocked over apredetermined length, each of said closure elements having differentcolors for establishing visually the completeness of the occlusion ofthe closure elements by providing a color different from the closureelements when said closure elements are occluded; wherein said femaleclosure element is translucent and said male closure element is opaque;wherein said opaque male closure element comprises a U-shaped channelelement including an element portion comprising a base portion having apair of spaced-apart, parallelly disposed webs integrally attached tosaid base portion and extending therefrom, said webs terminating inhooks, said hooks comprising hook portions facing away from each otherand having guide members integrally formed therewith and spaced adjacentto and apart from said webs; wherein said translucent female closureelement comprises a U-shaped channel element including an elementportion having a base portion with a pair of spaced-apart, parallellydisposed webs attached to said base portion and spaced to pass over saidwebs on said male closure element, wherein said webs on said femaleclosure element terminate in hooks extending toward each other to engageon said male enclosure element; with the provision that a translucentcolor change enhancement member is provided in the U-shaped channel ofat least one translucent closure element; and wherein the relationshipof the translucent closure element and the color change enhancementmember is defined by the relationship:

    H/Tan (Asin [N sin φ]-φ)+(H.sub.t -H)Tan φ≦D

where N is the index of refraction of the material used to make theclosure element; H is the height of the incident light ray above thebase of the closure element; H_(t) is the height of the color changeenhancement member as measured from the base of the closure element; φ(phi) is the angle at the top of the color change enhancement member; Dis the horizontal distance between the light incident first face of thecolor change enhancement and the intersection of the inner face of theinner web of the closure element and the closure base of the closureelement.
 25. The interlocking closure device of claim 21 or claim 22wherein in the width of the female closure element is between about 120mils and about 140 mils and the width of the male closure element isbetween about 170 mils and about 190 mils.
 26. The interlocking closuredevice of claim wherein the width of the female closure element isbetween about 125 mils and about 135 mils and the width of the maleclosure element is between about 175 mils and about 185 mils.
 27. Acontainer including two sidewalls and an interlocking closure deviceincluding male and female closure elements arranged to be interlockedover a predetermined length, each of said closure elements havingdifferent colors for establishing visually the completeness of theocclusion of the closure elements by providing a color different fromthe closure elements when said closure elements are occluded wherein atleast one of the closure elements is translucent, wherein theimprovement comprises the introduction of a translucent color changeenhancement member, having an index of refraction, in the internalchannel of a translucent closure element wherein said color changeenhancement member is effective in improving the perceivable colorchange between said male and female closure elements having differentcolors and the different color formed by occlusion of the differentlycolored male and female closure elements.
 28. A container according toclaim 27 including two sidewalls and an interlocking closure fasteningdevice wherein said interlocking closure fastening device including maleand female closure elements arranged to be interlocked over apredetermined length, each of said closure elements having differentcolors for establishing visually the completeness of the occlusion ofthe closure elements by providing a color different from the closureelements when said closure elements are occluded and wherein one closureelement is translucent; said male closure element including an elementportion comprising a base portion having a pair of spaced-apart,parallelly disposed webs integrally attached to said base portion andextending therefrom, said webs terminating in hooks comprising hookportions facing away from each other and hook projections facing awayfrom each other; said female closure element including an elementportion comprising a base portion having a pair of spaced-apart,parallelly disposed webs integrally attached to said base portion andspaced to pass over said webs on said male closure element and whereinsaid webs on said female closure element terminate in hooks extendingtoward each other to engage said hooks on said male closure element. 29.The container of claim 28 wherein said color change enhancement memberis characterized as having one face substantially parallel to said pairof spaced-apart, parallelly disposed webs.
 30. The container of claim 28wherein said color change enhancement member has a height less than theheight of said spaced-apart, parallelly disposed webs.
 31. The containerof claim 28 wherein the relationship between the spatial relationship ofthe translucent closure element and the geometry of the integrallyformed color change enhancement member is defined by the relationship:

    H/Tan (A sin [N sin φ]-φ)+(H.sub.t -H)Tan φ≦D

where N is the index of refraction of the material used to make theclosure element; H is the height of the incident light ray above thebase of the closure element; H_(t) is the height of the color changeenhancement member as measured from the base of the closure element; φ(phi) is the angle at the top of the color change enhancement member; Dis the horizontal distance between the light incident first face of theinner web of the closure element and the closure base of the closureelement.
 32. The container of claim 31 wherein the quantity

    H/Tan (A sin [N sin φ]-φ)+(H.sub.t -H) Tan φ

is less than D.
 33. A container according to claim 27 including twosidewalls and an interlocking closure device including male and femaleclosure elements having U-shaped channels arranged to be interlockedover a predetermined length, each of said closure elements havingdifferent colors for establishing visually the completeness of theocclusion of the closure elements by providing a color different fromthe closure elements when said closure elements are occluded, oneclosure element being opaque and the other closure element beingtranslucent; wherein the improvement comprises the introduction of arefractive translucent color change enhancement member in the internalchannel of said translucent closure element.
 34. A container accordingto claim 28 including two sidewalls and an interlocking closure deviceincluding male and female closure elements arranged to be interlockingover a predetermined length, each of said closure elements havingdifferent colors for establishing visually the completeness of theocclusion of the closure elements by providing a color different fromthe closure elements when said closure elements are occluded; whereinsaid male closure element is opaque and said female closure element istranslucent; wherein said opaque male closure element comprises aU-shaped channel element including an element portion comprising a baseportion having a pair of spaced-apart, parallelly disposed websintegrally attached to said base portions and extending therefrom, saidwebs terminating in hooks, said hooks comprising hook portions facingaway from each other and having guide members integrally formedtherewith and spaced adjacent to and apart from said webs; wherein saidtranslucent female closure element comprises a U-shaped channel elementincluding an element portion having a base portion with a pair ofspaced-apart, parallelly disposed webs attached to said base portion andspaced to pass over said webs on said male closure element, wherein saidwebs on said female closure element terminate in hooks extending towardeach other to engage on said male closure element; with the provisionthat a translucent color change enhancement member is in the U-shapedchannel of said translucent closure element.
 35. The container of claim34 having an interlocking closure device wherein the width of theclosure is greater than about 120 mils.